How to Appeal a Denied Insurance Claim: A Step-by-Step Guide
A denied claim is not the final word. You have the legal right to appeal — and appeals often succeed. Here's exactly how to do it.
Getting a claim denial from your insurance company can feel like a dead end. It isn't. Under federal law, you have the right to appeal any denied claim, and a significant percentage of appeals succeed when patients follow the right process.
Step 1: Understand why the claim was denied
Before you can appeal, you need to know the reason for the denial. This is on your Explanation of Benefits (EOB) as a reason code, and should also be in a separate denial letter from your insurer. Common denial reasons include:
- Not medically necessary — the insurer doesn't believe the service was required
- Out-of-network provider — you saw a provider not in your plan's network
- Prior authorization not obtained — approval was required before the service
- Service not covered — the procedure isn't included in your plan
- Coding error — the provider used an incorrect billing code
Step 2: Review your plan's Summary of Benefits and Coverage
Get a copy of your plan's Summary of Benefits and Coverage (SBC). Read the section that applies to the denied service. If the plan does cover the service and the denial seems incorrect, that's strong grounds for appeal.
Step 3: File an internal appeal
An internal appeal is a formal request to your insurer to review their decision. Under the Affordable Care Act, insurers must allow you to file an internal appeal, respond within 30 days for non-urgent claims, and provide a full and fair review by someone not involved in the original decision.
- Call member services and ask for the appeals department address and process
- Write a clear appeal letter stating the service, the denial date, and why you believe it should be covered
- Attach supporting documentation: your doctor's letter of medical necessity, relevant medical records, and a copy of the denial letter
- Send via certified mail so you have proof of receipt
- Keep copies of everything
Step 4: Request an external review if the internal appeal fails
If your internal appeal is denied, you have the right to an external review by an independent organization with no relationship to your insurer. Under federal law (the ACA), this right applies to most health plans. There is usually no cost to you for external review.
Step 5: File a complaint with your state insurance commissioner
You can file a complaint with your state's insurance regulatory office at any point. Find your state's insurance commissioner at the National Association of Insurance Commissioners (NAIC) website.
Tips that improve appeal success rates
- Get your doctor involved — a letter of medical necessity is the single most powerful piece of supporting evidence
- Be specific — reference the exact plan language, section, and page number you believe supports coverage
- Meet all deadlines — most plans require internal appeals within 180 days of the denial
- Document every conversation — note dates, times, and names when speaking with your insurer
Sources: Healthcare.gov — Appeals, CMS — External Appeals
